In the manufacturing of an integrated circuit (IC) product, the IC product is usually processed at many work stations or by many processing apparatuses. Transporting partially finished products is therefore conducted during the manufacturing process.
For example, to package an IC product, various steps of deposition, cleaning, ion implantation, etching and passivation may be carried out before the semiconductor substrates are packaged for shipment. Each of these fabrication steps may be performed in different processing machines. Therefore, the substrates that are partially processed are transported between various work stations many times before the fabrication process is complete.
In some systems, cassette pods are used to store batches of substrates. To transport the substrates, the substrates are moved into the cassette pods, and the cassette pods and the semiconductor substrates are transported together by handling and transport equipment. Operation of the handling and transport equipment may be conducted under automatic control using a programmed computer which issues control signals for operating the equipment with little or no intervention by an operator. Therefore the handling and transport equipment transports the cassette pods and the substrates between two positions for different purposes.
Although existing methods and devices for sending cassette pods have generally been adequate for their intended purposes, they have not been entirely satisfactory in all respects. Consequently, it is desirable to provide a solution for the process control for semiconductor manufacturing operations.